Helper function of cytolytic lymphocytes: Switching roles in the immune response

Giuseppina Li Pira, Federico Ivaldi, Laura Bottone, Gerrit Koopman, Fabrizio Manca

Research output: Contribution to journalArticlepeer-review


T helper (Th) cells and cytolytic T lymphocytes (CTL) play defined roles in the cellular immune response. This distinction wavered when Th lymphocytes were shown to kill antigen-presenting cells displaying the relevant antigen. Here we demonstrate that also the opposite can be true: CTL can exert helper functions. We noticed that certain CMV-specific CTL lines grew after antigen activation also without exogenous IL-2. These lines produced their own IL-2, which supported the expansion of other CTL and Th cell lines. High levels of helper cytokines like IL-4, IL-5 and IL-6 were detected in the culture supernatants. Thus, we set up a helper assay to study the functional interactions between T cells (or their supernatants) and B cells. Conditioned media from helper CTL lines induced secretion of antigen-specific antibodies by B cells pulsed with antigen as first signal. We conclude that it is possible to isolate CTL lines that exhibit helper functions for T cells and B cells. If this possibility is proven also in vivo, we should revise some of our views on the pathogenesis of diseases in which CD8 cells are key players, such as in viral infections, graft rejection and GVHD.

Original languageEnglish
Pages (from-to)66-77
Number of pages12
JournalEuropean Journal of Immunology
Issue number1
Publication statusPublished - Jan 2007


  • CMV
  • CTL
  • Cytokines
  • Helper function
  • T cell lines

ASJC Scopus subject areas

  • Immunology


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